Gain enhancement of microstrip patch antenna using near-zero index metamaterial (NZIM) lens

In this paper, an array of 7 × 7 novel compact metamaterial unit cells is used as superstrate to improve the broadside gain of a microstrip patch antenna operating at the WLAN band. The proposed unit cell is obtained by suitably adding extra metal strips to the conventional mirrored S like structures. The unit cell cell analysis and parameter extraction using periodic boundary condition confirms the near zero index behavior as well as significant reduction (almost 52%) in the unit cell footprint. Simulation and measurement results confirm that near-zero index metamaterial (NZIM) lens significantly improves the gain (by more than 2 dBi) and reduces the half power beamwidth in both E-plane and H-plane by 20°.